The present invention relates to devices for fastening to rock, and more particularly to removable rock anchors for use in the sport of mountain climbing.
In the sport of mountain climbing, climbers rely on the use of safety ropes which are removably secured to the face of the rock at selected points during the climb, and during the climb the rope is advanced from one attachment point to the next. The rope may be secured to the rock either directly, or by means of a variety of available devices. There are two types of attachment means for use in rock climbing: those which are permanently affixed to the face of the rock, and those that are removable and reusable as the climb progresses.
The devices for permanent attachment include pitons and bolts which are driven into the rock to which the safety rope is slidably affixed. This requires that the climber not only carry the heavy pitons, enough for the entire climb, but also heavy tools for driving them into the rock. Additionally, these devices have negative safety and esthetic value. With time the pitons rust, stain the face of the rock and grow weak. The rust weakened pitons then provide a questionable anchor to subsequent climbers, and could break off and be the resultant cause of injury to a climber that chooses to rely on them.
In recent years, climbers have been increasingly concerned with the safety and esthetic problems with pitons, and have been seeking ways to make "clean" climbs. To this end, a number of removable and reusable climbing devices have appeared on the market.
These include a variety of climbing chocks of various shapes that are forced into a crack and have a hole through them for receiving a rope. These can be hard and time-consuming to place since the climber may only have a limited number of sizes of chocks with him on the climb, the available cracks may be too large or small to properly accomodate those sizes, and chocks have no moving parts to ease their placement while the climber holds onto the face of the rock with his toes and fingertips. Once placed, they nearly always require the use of a chock clean-up tool to break them free so that they can be recovered. U.S. Pat. No. 4,442,607 discloses a typical climbing chock.
Another device which is known to rock climbers as a "friend" is disclosed in U.S. Pat. No. 4,184,657. This device includes a support bar, a spindle mounted on the support bar, two pairs of cam members pivotally mounted on the spindle adapted for opposite pivotal movement from a "closed" position to an "open" position, and spring members mounted on the spindle between each pair of cam members which act to apply force to each cam member to urge it into its open position. An operating bar is slidably mounted on the support bar and is connected to each cam member, there being at the opposite end of the support bar to the spindle an attachment point for a climbing rope. By pulling the operating bar away from the spindle puts the cams into the "closed" position so that the climbing aid can be inserted into a crack formed in rock or the like. Once placed, the bar is then released and the spring members force the cams into their "open" position to lock the climbing aid within the crack. The support bar may also include means to hold the operating bar in a position where the cam members are in the "closed" position. The "friend" presents a problem in that it can only be used in fairly large cracks in the rock as a result of the diameter of the cams, the number of cams, and the spacing between those cams. A major drawback to this device is that once placed in a crack, it has a tendency to walk into the crack, which in some cases makes retrieval impossible since the operating bar can no longer be reached to "close" the cams for removal. The loss of only a few of these devices on a climb can quickly make that climb expensive due to the substantial cost of these devices.
Yet another device which has recently been introduced is a two section chock in the shape of a parallelogram when the two sections are aligned one with the other. One chock section is affixed to one end of an anchor cable with the other end of the cable folded back and clamped to itself to form an anchor loop. The other chock section is mounted on a second cable with its other end connected to a disk which surrounds the anchor cable so that the two cables are parallel to each other. There also is a coil spring around the anchor cable between the loop and the disk to bias the other chock section upward. Further, there is a plastic sleeve around both cables adjacent the disk to protect them and to limit the extent to which the spring can bias the other chock section upward. This is limited so that no less than one-half of each chock section is adjacent the other at all times. Finally, to maintain the two chock sections in a juxtaposed position, they are dove-tailed together. Thus, by pulling the disk toward the anchor loop, the other chock section slides past the one chock section thus making the effective combined thickness of the two chock sections variable. This permits the thinning of the combined chock for insertion into a crack and then the thickening of the combined chock when the disk is released. In this design, the long parallel face of each chock section makes contact with the inner surfaces of the crack, usually at a single point on each face. The points of contact tend to be uneven and unsymmetrical from one face to the other due to the unevenness of the faces of the crack. As the climber advances up the face of the rock while using these anchoring devices, his safety rope may pull on the anchor loop causing rotation of the chock about its faces. In doing so, these devices often become unwedged and therefore useless to the climber should he fall after climbing past such a placement. In addition, if a fall occurs and a wedged one of these devices breaks that fall, the chock sections may twist making its recovery very difficult, if at all, only with the use of a hammer and punch, wherein the hammer and punch represent extra weight that a climber would rather not carry. If this device is not recoverable and must be left behind, it too represents an expensive permanent placement, much more expensive than simple pitons. Further, these devices have been found not to work well in flaring cracks and they have a tendency to slip in smooth cracks on their smooth faces.
What is needed is a variable thickness chock design that can be made in a variety of sizes and widths, one that is easily placed and can be used in all types and orientations of cracks including flaring cracks, one that can be placed without having to view the crack while doing so, one that maintains its wedge when the anchor loop is pulled as the climber climbs around the point of placement, and one that is easily retrievable when the clean-up man reaches the placement. The present invention provides such a device.